Define what you mean by 'system blocks'. The code you posted does alternative things depending on the selection in ComboBoxDocType. What is it that is not happening that you expect to happen?

Select Case ComboBoxDocType.ListIndex
    Case Is = 0    'First item in list
        If ListBoxCoC.Text = "General Comments" Then
            AutoTextToBM "EVTBookMark01", ActiveDocument.AttachedTemplate, "GeneralComments"
        End If
        If ListBoxCoC.Text = "Specific Comments" Then
            AutoTextToBM "EVTBookMark02", ActiveDocument.AttachedTemplate, "SpecificComments"
        End If
    Case Is = 1    'Second item in list
        AutoTextToBM "EVTBookMark01", ActiveDocument.AttachedTemplate, "Table"
    Case Else    'Nothing selected
End Select